Numerous warning signs and labels exist to warn of the presence of hazards in the surrounding environment. All of these warning signs and labels are displayed by a user with prior knowledge of the existence of the hazard so as to warn and alert others. For example, a warning sign having a flame shape or the word "FLAMMABLE" can be displayed by the user next to flammable substances to warn others of the existence of these substances.
Colorimetric dosimeter devices have been developed for measuring the concentration levels of gaseous hazards or pollutants in the ambient atmosphere surrounding the dosimeter. Colorimetric dosimeters are also available commercially as portable devices or badges. The conventional dosimeter badge contains a color-forming reagent impregnated in paper, which reacts by changing color in the presence of a particular gastapor. The intensity of the color change is proportional to the concentration of the reactive gas/vapor and the time of exposure. This relationship allows the observer to compare the received color to a standard color to determine the real exposure. However, the conventional dosimeter badge does not, by itself, function as a warning sign or a warning label.
In the present invention, the user has knowledge of the potential existence of the hazard but the warning sign appears only when the targeted hazard starts to exist even in very small quantities, not dangerous to health, allowing the user to take corrective measures As the amount of the targeted hazard increases in the surrounding environment, the color and intensity of the warning sign increases in a direct proportional manner to the concentration of the hazard. This feature gives the self-appearing warning sign dosimetric properties enabling the user to estimate or accurately measure, in real time, the amount of hazard in the surrounding environment. The self-appearing warning sign of the present invention is a base for light-weight and low-cost colorimetric dosimeters suitable as disposable devices or warning labels. The device made upon the present invention is scratchproof and virtually waterproof suitable for harsh indoor and outdoor industrial environments.